Tether Limited is a financial technology company that issues the Tether stablecoin (USDT), the world’s largest stablecoin by market capitalization. Founded in 2014, Tether pioneered the concept of fiat-backed digital currencies pegged 1:1 to traditional currencies. USDT has become a key source of liquidity in the cryptocurrency market, with over $170 billion in tokens circulating as of 2025. Tether Limited is privately owned and has grown into one of the most valuable fintech companies; in 2025 it was reportedly seeking to raise capital at a valuation of around $500 billion, which would place it among the world’s most valuable firms.